Aircraft Maintenance Licence Categories: A, B1, B2, B3 and C Explained
Every aircraft maintenance engineer licence is divided into categories that define exactly what an engineer can certify. Whether you train under EASA Part-66 or India’s DGCA CAR-66, understanding categories A, B1, B2, B3 and C is essential to choosing your training path and your future role in the hangar or on the line.
Why licence categories matter
Aircraft maintenance engineer licences are not one-size-fits-all. Both the European EASA Part-66 framework and India’s DGCA CAR-66 divide the licence into categories that define exactly what type of work an engineer is authorised to certify. Understanding these categories is one of the first things every aspiring AME needs to grasp, because they determine your training path, the modules you sit, and the kind of aircraft and systems you can sign off.
The main licence categories
Under EASA Part-66 — which DGCA CAR-66 closely mirrors — the aircraft maintenance licence is issued in several categories and subcategories. Each is tied to a defined scope of certification privileges.
| Category | Scope | Typical work |
|---|---|---|
| A | Line maintenance, limited tasks | Minor scheduled servicing, simple defect rectification |
| B1 | Mechanical systems | Airframe, engines, mechanical and electrical systems |
| B2 | Avionics | Electrical and avionics systems, instruments, autoflight |
| B3 | Piston non-pressurised aeroplanes | Light piston aircraft below a defined weight |
| C | Base maintenance | Certification of base (heavy) maintenance for large aircraft |
Category B1 and B2 in detail
The B1 and B2 categories form the backbone of the profession. A B1 engineer works across the airframe, powerplant, and the mechanical and electrical systems of the aircraft, while a B2 engineer specialises in avionics and electrical systems. B1 is further divided by aircraft type — such as turbine aeroplanes, piston aeroplanes, turbine helicopters and piston helicopters — so the privileges always match the technology the engineer has been trained on.
Category C and base maintenance
The Category C licence is aimed at base maintenance on large aircraft. A C-licence holder does not personally perform every task; instead, they issue the certificate of release to service for the aircraft as a whole after the underlying tasks have been carried out and certified by B1 and B2 staff. For this reason, the C category usually requires prior experience as a B1 or B2 engineer, or an appropriate academic background.
How to choose your path
- Decide between mechanical and avionics early. If you are drawn to engines, structures and mechanical systems, B1 is your route; if electronics, instruments and avionics fascinate you, aim for B2.
- Match the category to your career goal. Line maintenance roles lean on A and B licences, while heavy maintenance and hangar leadership often require Category C.
- Plan your type ratings. Holding a category is only the start — you also need aircraft type training endorsements to certify specific models.
EASA and DGCA: the same logic
Because DGCA CAR-66 was modelled on EASA Part-66, the category structure is broadly equivalent, which makes it easier for engineers to understand both systems and, in some cases, to convert qualifications between them. Whichever framework you train under, the categories tell you and your employer precisely what you are competent and authorised to certify — the foundation of safe, accountable maintenance.